Apple reported shipments of its Mac computer were the strongest in years this quarter, while sales of the iPad slid for a third consecutive quarter.

"Some of the weakness in iPad can be explained, I think, by the strength in MAC, but the fact is they have differentiated products and having put them in schools for the last 10 to 15 years has aided the product line," said Steven Milunovich, managing director at UBS.

Justin Solomon | CNBC

Apple iPad Air 2

Milunovich said the the ease of use of the MAC remains well ahead of Windows and will continue to benefit Apple PC sales.

"The strength in PC sales to some degree is coming at the expense of the tablet market. I think what it says is that there's a fairly clear delineation between what you can do with a tablet and what you can do with a PC and in particular the ability what you can create content is much greater with a PC," said Milunovich.

Milunovich doesn't think the downward trend in iPad sales will be reversed any time soon.

"The iPad's really kind of caught between; at the low end the phone is moving up, particularly the iPhone 6 Plus, the Phablet, and at the high end, again, people have a really good sense of what the PC can do versus the tablet," Milunovich said.

He thinks the tablet market appears to be saturated in the short term. "One of the issues here is that upgrade cycle for iPads is longer than phones, probably on the order of four years, and we're probably going to see that improve ahead of us," said Milunovich.